The invention relates to a domestic appliance having at least one rotatably driven tool projecting from a housing, where the tool is movable axially during normal operation.
Such a domestic appliance is mentioned as prior art in the Swiss patent document CH 349 389 and is therefore known. The Swiss document discloses a domestic appliance constructed so that a tool is movable in an axial direction under the influence of gravity. Under the influence of gravity at least this one tool is held in contact with the container wall, for example the bottom of a container for holding foodstuffs to be processed, in a more or less satisfactory manner. Patent document CH 349 389 does not give any concrete details about the construction of the prior art described therein, so that the conclusion is obvious and permissible that also with this known construction the two tools are movable in axial directions under the influence of gravity. Though in many cases the movement of tools of a domestic appliance under the influence of gravity may lead to satisfactory results this is not always the case. For example, if the foodstuffs to be processed offer a comparatively high mechanical resistance to the tools, the tool load under the influence of gravity may be inadequate too keep all the tools applied to the bottom of the container holding the foodstuffs. Moreover, this condition may give rise to jerky axial movements, which feel unpleasant to a user who handles the domestic appliance. This prior art construction should therefore be regarded as not user-friendly.
It is an object of the invention to preclude the afore-mentioned problems and to provide an improved domestic appliance.
According to the invention, such an appliance has a spring urging the tool away from the housing, and a user controllable blocking device for blocking the tool from axial movement against the spring force.
The user controllable blocking device permits normal operation in a movement-permitted mode, in which sufficient force against the respective free end of one or more tools causes the tool or tools to be depressed into the housing, thereby deflecting the spring for each affected tool, or normal operation in a movement-blocked mode preventing depression of any of the tools in a direction parallel to the tool axis. The blocking device is movable between a blocking position and a release position. Each tool, when the blocking device is in its blocking position, is blocked against movement of the tool against the force of the spring means which loads the tool while still being normally operable. As a result, the user can select whether the tool axial position will conform to the shape of a container in which a foodstuff is being mixed or otherwise processed, or the free ends of the tools will invariably be held in a predetermined relative axial position determined by the lengths of the respective tools.
In a preferred embodiment, the blocking device includes a blocking sleeve for each tool, connected to a sleeve mount arranged to be moved transversely to the tool axis between a position in which the blocking sleeve is interposed between the spring for that tool and an inner sleeve in which the tool is held. This arrangement allows operation of a tool ejection device, by which the part of each tool inside the respective inner sleeve can be moved out of the inner sleeve to enable ejection of the tool.
According to a further preferred embodiment of the invention, the sleeve mount is pivotable about a pivotal axis which is oriented parallel to the tool axis. When the appliance has two tools parallel to each other, the pivotal axis is preferable midway between the axes of the two tools.
According to another preferred embodiment of the invention, the ejector device includes a respective ejector pin for each tool, arranged such that the sleeve mount is located axially between the ejector device and the inner and outer sleeves. The outer sleeves are driven rotationally and impart rotation to the inner tool-holding sleeves which are axially slidable in the respective outer sleeves. To eject the tools, the ejector pins pass through openings in the sleeve mount to engage the ends of the tools in the inner sleeves when the blocking device is in the release position, and pass through the respective blocking sleeves to engage the ends of the tools in the inner sleeves when the blocking device is in the blocking position. Thus ejection is independent of the blocking device position.
These and other aspects of the invention will become apparent from the embodiment described hereinafter by way of example and will be elucidated with reference to this example.